Picked up a cheap supposedly 20% underdrive crank pulley from summit. They have the option to do crank and alternator but i dont want charging problems. Keep in mind my truck lives at 2500-3500 as a daily driver, so I dont need a whole lot of alternator or AC rpm. plus frees up a shave of torque.

Took about an hour to install, including fetching the belts from oreilly's. Easily doable over a lunch break with hand tools.

Crank bolts are 1/2". I just reused the old ones and flooded them in blue locktite.

I still need to get a high power diode and hook the water pump to my Spod. Also, relocating the electric motor now requires a 25" cog belt.

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What will it do?

 

Kinda glad I didnt get the alternator kit. Idle charging voltage is 12.6 with high beams, radiator fan, and HVAC fan on for a full electrical load.

 

I thought the alternator one sped up the alternator so it works correctly (that's how the GM ones work anyway)

 

That may be the case, but in the photos I saw, the alternator pulley was pretty dang big. That said, not alot of room on the alt to go to a smaller pulley.

But it shouldnt affect me too much unless i'm sitting in traffic at night. I turned the headlights off and they're worth .3 of a volt, HVAC blower is worth about .15, and radiator is worth about .6 of a volt. Most of my commute is at 2500-3500 RPM where it still makes 14.1-14.5 volts.

The main purpose was to slow down the AC compressor and (to a certain extent) the alternator. I have the P/S unhooked and normally run an electric water pump, so those are 2 parasitic loads I don't have to really worry about.

Next project is to remove any unneccesary weight, starting at the spare tire winch crossmember, and also do something with the exhaust before it falls the rest of the way off. Also need to figure out which pulley is sqeaking and figure out of my ignition coil or the MSD box died, so I can have my 2 step back.